A common origin of all the species of high-energy cosmic rays?

Cosmic ray nuclei, cosmic ray electrons with energy above a few GeV, and the diffuse gamma-ray background radiation (GBR) above a few MeV, presumed to be extragalactic, could all have their origin or residence in our galaxy and its halo. The mechanism accelerating hadrons and electrons is the same, the electron spectrum is modulated by inverse Compton scattering on starlight and on the microwave background radiation; the $\gamma$-rays are the resulting recoiling photons. The spectral indices of the cosmic-ray electrons and of the GBR, calculated on this simple basis, agree with observations. The angular dependence and the approximate magnitude of the GBR are also explained.Comment: Includes a discussion of the contribution of inverse Compton scattering of CR electrons by starlight in the halo to the gamma background radiation. One corrected typo. Additional references, and figures to compare predictions for the angular dependence of the gamma background radiation with data. Conclusions are unchange

Two-dimensional droplet spreading over random topographical substrates

We examine theoretically the effects of random topographical substrates on the motion of two-dimensional droplets via appropriate statistical approaches. Different random substrate families are represented as stationary random functions. The variance of the droplet shift at both early times and in the long-time limit is deduced and the droplet footprint is found to be a normal random variable at all times. It is shown that substrate roughness decreases droplet wetting, illustrating also the tendency of the droplet to slide without spreading as equilibrium is approached. Our theoretical predictions are verified by numerical experiments.Comment: 12 pages, 5 figure

On the Galactic Evolution of DD and 3He^3He

The determined abundances of primordial $^4He$ and $^7Li$ provide a basis with which to test the standard model of big bang nucleosynthesis in conjunction with the other two light element isotopes $D$ and $^3He$, also produced in the big bang. Overall, consistency in the standard big bang nucleosynthesis model is best achieved for a baryon-to-photon ratio of typically $3 \times 10^{-10}$ for which the primordial value of $D$ is five times greater than the present observed abundance and about three times greater than the pre-solar value. We consider various models for the chemical evolution of the Galaxy to test the feasibility for the destruction of D without the overproduction of $^3He$ and overall metallicity. Models which are capable of achieving this goal include ones with a star formation rate proportional to the gas mass fraction or an exponentially decreasing star formation rate. We discuss the effect of parameters that govern the initial mass function and of surviving fractions of $^3He$ in stars between one and three solar masses.Comment: 25 pages, LaTeX, UMN-TH-1206/9

Age, sex, adult and larval diet shape starvation resistance in the Mediterranean fruit fly: an ecological and gerontological perspective.

The ability of an animal to withstand periods of food deprivation is a key driver of invasion success (biodiversity), adaptation to new conditions, and a crucial determinant of senescence in populations. Starvation resistance (SR) is a highly plastic trait and varies in relation to environmental and genetic variables. However, beyond Drosophila, SR has been studied poorly. Exploiting an interesting model species in invasion and ageing studies-the Mediterranean fruit fly (Ceratitis capitata)- we investigated how age, food and gender, shape SR in this species. We measured SR in adults feeding in rich and poor dietary conditions, which had been reared either on natural hosts or artificial larval diet, for every single day across their lifespan. We defined which factor is the most significant determinant of SR and we explored potential links between SR and ageing. We found that SR declines with age, and that age-specific patterns are shaped in relation to adult and larval diet. Females exhibited higher SR than males. Age and adult diet were the most significant determinants of SR, followed by gender and the larval diet. Starvation resistance proved to be a weak predictor of functional ageing. Possible underlying mechanisms, ecological and gerontological significance and potential applied benefits are discussed

Geometric variations of the Boltzmann entropy

We perform a calculation of the first and second order infinitesimal variations, with respect to energy, of the Boltzmann entropy of constant energy hypersurfaces of a system with a finite number of degrees of freedom. We comment on the stability interpretation of the second variation in this framework.Comment: 9 pages, no figure

Conditions for duality between fluxes and concentrations in biochemical networks

Mathematical and computational modelling of biochemical networks is often done in terms of either the concentrations of molecular species or the fluxes of biochemical reactions. When is mathematical modelling from either perspective equivalent to the other? Mathematical duality translates concepts, theorems or mathematical structures into other concepts, theorems or structures, in a one-to-one manner. We present a novel stoichiometric condition that is necessary and sufficient for duality between unidirectional fluxes and concentrations. Our numerical experiments, with computational models derived from a range of genome-scale biochemical networks, suggest that this flux-concentration duality is a pervasive property of biochemical networks. We also provide a combinatorial characterisation that is sufficient to ensure flux-concentration duality. That is, for every two disjoint sets of molecular species, there is at least one reaction complex that involves species from only one of the two sets. When unidirectional fluxes and molecular species concentrations are dual vectors, this implies that the behaviour of the corresponding biochemical network can be described entirely in terms of either concentrations or unidirectional fluxes

Geometry-induced phase transition in fluids: capillary prewetting

We report a new first-order phase transition preceding capillary condensation and corresponding to the discontinuous formation of a curved liquid meniscus. Using a mean-field microscopic approach based on the density functional theory we compute the complete phase diagram of a prototypical two-dimensional system exhibiting capillary condensation, namely that of a fluid with long-ranged dispersion intermolecular forces which is spatially confined by a substrate forming a semi-infinite rectangular pore exerting long-ranged dispersion forces on the fluid. In the T-mu plane the phase line of the new transition is tangential to the capillary condensation line at the capillary wetting temperature, Tcw. The surface phase behavior of the system maps to planar wetting with the phase line of the new transition, termed capillary prewetting, mapping to the planar prewetting line. If capillary condensation is approached isothermally with T>Tcw, the meniscus forms at the capping wall and unbinds continuously, making capillary condensation a second-order phenomenon. We compute the corresponding critical exponent for the divergence of adsorption.Comment: 5 pages, 4 figures, 5 movie

Patterns in the Sacred Music Culture of the American South and West (1700-1820)

This narrative chronicles the dissemination of sacred music from the eastern seaboard to the West and South spanning a time frame from the colonial era to the latter part of the Early Nationalist Period (1700-1820). Musical culture in its migration away from the eastern seaboard also parallels the greater western and southern expansion of the United States from its initial configuration of localized regional subgroups to the beginnings of a larger national identity. From this conceptual base, sacred music becomes a vehicle for understanding not only religious and musical changes over time, but also the broader maturity of a nation. Focusing on this period allows for inquiries both into the development of hymnody in the Middle Atlantic, and the subsequent developments of the West and South. These chronological delimitations allow for a discussion of musical practice beginning with formative sacred music developments and continuing to the incorporation of techniques shaped by reform-minded musicians from the eastern seaboard. The following topics guided the construction of this thesis: explicating how the Middle Atlantic region shaped compositional trends, aesthetic, and performance practice of the American West and South; identifying the various southern cultures as understood by eighteenth and nineteenth-century southerners and their application to sacred music practice; understanding how nineteenth-century Americans distinguished between the West and the South; understanding how southern and western music relates to individual denominations and cultures within these areas; and understanding performance practice common to the evangelical and non-evangelical branches of individual sects. Identifying patterns of development in American sacred music of the South and West involves documentation of performance practice, denominational aesthetics, and tunebook bibliography. The study of eighteenth-and-nineteenth-century material by twentieth-and-twenty-first-century writers has falsely defined cultural borders of this region according to a post-bellum conceptualization of the boundaries of the North and South. Prior to 1850, writers defined their borders according to a different set of geographic boundaries than today. Consequently, this thesis differs in terms of geographic and cultural definitions of the North and South from current scholarship because of this writer’s application of colonial and Early Nationalist understandings of American culture